Lubrication systems, such as those used in aircraft gas turbine engines, supply lubricant to bearings, gears and other engine components that require lubrication. The lubricant, typically oil, cools the components and protects them from wear. A typical oil lubrication system includes conventional components such as an oil tank, pump, filter and oil supply conduits.
If one of the lubrication system components fails, malfunctions or sustains damage, the oil supply to the lubricated component may be disrupted resulting in irreparable damage to the component and undesirable corollary consequences. For example, if an engine oil pump fails or a supply conduit develops a severe leak, the resulting loss of oil pressure could disable the engine by causing overheating and/or seizure of the bearings that support the engine rotor. An aircraft engine that becomes disabled in flight is obviously a concern, especially for a single engine military aircraft operating in hostile airspace.
It is known to accommodate the possibility of a failure in the oil system by configuring the system so that it continues to supply oil to the lubricated components for a limited time thereby enabling continued temporary operation of the engine. Such a system allows the aircraft crew time to safely shut down the engine or to take other appropriate actions to safeguard the aircraft and its occupants. In a military aircraft, such a system can provide the crew with valuable additional time to return to friendly airspace.
While it it desirable to employ a lubrication system that accommodates failure of system components, it is also highly desirable that the system be reliable and maintenance free and that it operate passively, i.e. without dedicated sensors, control systems or actuators. In an aircraft application, it is also important that the system be light weight, compact and inexpensive. For combat aircraft, it is also desirable that the system be shielded from potential battle damage.